Usain Bolt once again produced his best when it mattered most to retain his 100 metres world title yesterday and reassert his status as the fastest man on the planet.

The 29-year-old Jamaican surged past the in-form American Justin Gatlin over the last 30 metres and crossed the line in 9.79 seconds, his fastest run of the year.

Gatlin finished second in 9.80 to take silver, while Andre de Grasse of Canada and American Trayvon Bromell finished together in third place in a time of 9.92.

They will both be awarded bronze medals after they ran identical times down to a 1000th of a second.

Bolt, the reigning Olympic champion and world record holder, has now not been beaten in the 100m or 200m in six major global championships going back to 2007.

“This definitely means a lot because I’ve been struggling all season,” Bolt, who has battled for form in an injury-disrupted season, said.

“It took me a while to figure out what was the problem and get it together. So I’m just happy.”

He was disqualified from the shorter race at the Daegu world championships in 2011, however, and flirted with a similar mishap when he stumbled out of the blocks in the semi-finals earlier yesterday.

Usain Bolt wins the 100 metres final in Beijing, yesterday.

There were no mistakes when it came to final, though, and, back at the stadium where he first rocketed into the sporting stratosphere at the 2008 Beijing Olympics, he powered down lane five to edge Gatlin.

The 33-year-old American, a world and Olympic champion before the rise of Bolt and his four-year doping ban, will perhaps regret dipping for the line quite so far out, a move which disrupted his rhythm and reduced his speed.

The victory for Bolt will be an undoubted boost for a sport which has spent three weeks locked in a public relations crisis after allegations of widespread doping among athletes.

“I understand why (people thought it was important for me to win),” Bolt added.

“But as I said, I wanted to do it for myself. It was a big deal.”

Bolt will go for successive world championship sprint sweeps in Beijing with the 200 metres final scheduled for Thursday.

Spain’s Miguel Angel Lopez hauled in Wang Zhen to win the men’s 20 kilometre race walk and deny China their first gold medal of their home championships.

The 27-year-old European champion hung tough as a group of five Chinese walkers, led by Wang, tried to stretch the pace from the start but the group splintered under the strain and Lopez had enough stamina to hit the front in the closing stages.

He passed Wang at the 18-km mark and pumped his fist in delight as he crossed the line in a personal best time of one hour 19 minutes 14 seconds, 15 seconds ahead of the Chinese.

American Joe Kovacs won the men’s shot put gold medal, denying defending champion David Storl of Germany a hat-trick of titles.

The 26-year-old from Pennsylvania left it late and threw 21.93 metres in the fifth round to become the first American since 2009 to win the shot world title.

Poland’s Pawel Fajdek underlined his dominance of the men’s hammer this year when winning the title with an 80.88 mark.

Wingfield disqualified

In the women’s 100m, there was heartache for Maltese sprinter Charlotte Wingfield who was disqualified for a false start in the second heat.

Nigeria’s Blessing Okagbare won the race in 11.07 seconds ahead of Jamaica’s Natasha Morrison who clocked 11.08.